Sensor detection pads with integrated fuse

ABSTRACT

A monitor system to monitor a characteristic of a user is disclosed. A monitor system includes a sensor producing signals indicative of glucose characteristics within the user. The sensor has a connector with a plurality of contacts, at least two contacts being shorted by a fuse trace. The monitor system further includes an electronics package with a package housing. The package housing contains a battery, a package port interfaced with the connector to receive signals from the sensor, and a package processor to process the signals from the sensor. Further included in the monitor system is a fuse system controlled by the package processor that includes a fuse timer, wherein the fuse trace is destroyed after the fuse timer reaches a threshold value.

RELATED APPLICATION

The present disclosure is a Divisional of U.S. patent application Ser.No. 14/244,132 filed on Apr. 3, 2014, the contents of which are hereinincorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention relates to monitor systems and, in particularembodiments, to devices and methods for operation of a sensor todetermine a characteristic of a body.

BACKGROUND OF THE INVENTION

Over the years, bodily characteristics have been determined by obtaininga sample of bodily fluid. For example, diabetics often test for bloodglucose levels. Traditional blood glucose determinations have utilized apainful finger prick using a lancet to withdraw a small blood sample.This results in discomfort from the lancet as it contacts nerves in thesubcutaneous tissue. The pain of lancing and the cumulative discomfortfrom multiple needle pricks is a strong reason why patients fail tocomply with a medical testing regimen used to determine a change incharacteristic over a period of time. Although non-invasive systems havebeen proposed, or are in development, none to date have beencommercialized that are effective and provide accurate results. Inaddition, all of these systems are designed to provide data at discretepoints and do not provide continuous data to show the variations in thecharacteristic between testing times.

A variety of implantable electrochemical sensors have been developed fordetecting and/or quantifying specific agents or compositions in apatient's blood. For instance, glucose sensors have been developed foruse in obtaining an indication of blood glucose levels in a diabeticpatient. Such readings are useful in monitoring and/or adjusting atreatment regimen which typically includes the regular administration ofinsulin to the patient. Thus, blood glucose readings improve medicaltherapies with semi-automated medication infusion pumps of the externaltype, as generally described in U.S. Pat. Nos. 4,562,751; 4,678,408; and4,685,903; or automated implantable medication infusion pumps, asgenerally described in U.S. Pat. No. 4,573,994, which are hereinincorporated by reference. Typical thin film sensors are described incommonly assigned U.S. Pat. Nos. 5,390,671; 5,391,250; 5,482,473; and5,586,553 which are incorporated by reference herein, also see U.S. Pat.No. 5,299,571. However, the monitors for these continuous sensorsprovide alarms, updates, trend information and require sophisticatedhardware to allow the user to program the monitor, calibrate the sensor,enter data and view data in the monitor and to provide real-timefeedback to the user. This sophisticated hardware makes it mostpractical for users that require continuous monitoring with feedback tomaintain tight control over their conditions. In addition, these systemsrequire the user to be trained in their use, even if to be worn forshort periods of time to collect medical data which will be analyzedlater by a doctor.

Doctors often need continuous measurements of a body parameter over aperiod of time to make an accurate diagnosis of a condition. Forinstance, Holter monitor systems are used to measure the EKG of apatient's heart over a period of time to detect abnormalities in theheart beat of the patient. Abnormalities detected in this manner maydetect heart disease that would otherwise go undetected. These tests,while very useful are limited to monitoring of bio-mechanical physicalchanges in the body, such as a heart beat, respiration rate, bloodpressure or the like.

Electrochemical sensors typically have a well-defined finite time ofuse. Contributing to the finite life is the consumption or reaction ofchemical reagents that allow the sensor to detect the desired agents andcompositions. Upon consumption of the sensor reagents it is possible toget spurious or inaccurate readings from a sensor. It is thereforeundesirable and even potentially dangerous to use a sensor beyond itsdesigned lifetime. Despite the known dangers, there are documented casesof sensors being used well beyond their design lifetime. In order toprovide accurate data and optimized care, it would be beneficial to havea sensor capable of turning itself off after a specified design lifetimehas elapsed.

SUMMARY OF THE DISCLOSURE

In one embodiment a monitor system to record a characteristic of a useris disclosed. The monitor system includes a sensor to produce signalsindicative of a glucose characteristic measured in the user. The sensorincludes a connector with a plurality of contacts where at least two ofthe contacts being shorted by a fuse trace. The system further includesan electronics package that includes a package housing that contains, abattery, a package port interfaced with the connector to receive signalsfrom the sensor, and a package processor to process the signals from thesensor and store the processed signals in non-volatile memory. Furtherincluded in the package housing is a fuse system controlled by thepackage processor that includes a fuse timer. Wherein the fuse trace isdestroyed after the fuse timer reaches a threshold value.

In another embodiment a monitor system to transmit a real-timecharacteristic of a user is disclosed. The monitor system includes asensor to produce signals indicative of a glucose characteristicmeasured in the user, the sensor having a connector with a plurality ofcontacts, at least two contacts being shorted by a fuse trace; and anelectronics package that includes a package housing, a battery beingcontained within the package housing, a package port interfaced with theconnector to receive the produced signals from the sensor, a packageprocessor to process the produced signals from the sensor and transmitthe processed signals via a transmitter, a fuse system controlled by thepackage processor that includes a fuse timer; wherein the fuse trace isdestroyed after the fuse timer reaches a threshold value.

Other features and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings which illustrate, by way of example, variousfeatures of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of embodiments of the invention will be made withreference to the accompanying drawings, wherein like numerals designatecorresponding parts in the several figures.

FIG. 1 is an exemplary illustration of components of a monitor system,in accordance with embodiments of the present invention.

FIGS. 2A-2C are exemplary illustrations of placement of a sensor andinstallation of the electronics package onto the sensor, in accordancewith embodiments of the present invention.

FIG. 3 is an exemplary block diagram illustrating components within theelectronics package, in accordance with one embodiment of the presentinvention.

FIGS. 4A-4D are exemplary views of the fuse circuit in accordance withembodiments of the present invention.

FIG. 5A is an exemplary illustration of package port that would receivethe connector from the sensor, in accordance with one embodiment of thepresent invention.

FIGS. 5B-5D illustrate various embodiments of detail of the recorderport, in accordance with embodiments of the present invention.

FIG. 6 is an exemplary flow chart illustrating operations to initiate asensor with a fuse, in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

As shown in the drawings for purposes of illustration, the invention isembodied as a component within a subcutaneous implantable analyte sensorset that provide continuous data of the sensor readings to a portableinfusion system. In some embodiments the sensor data is recorded intomemory integrated into an electronics package that also provides powerand wireless communication capability to the sensor. In otherembodiments the sensor transmits sensor readings to an infusion pumpthat can include memory to store the sensor readings. The recordedsensor readings or data can later be downloaded or transferred to acomputing device to determine body characteristic data based on the datarecording over the period of time. In embodiments of the presentinvention, the analyte sensor set and monitor system are for determiningglucose levels in the blood and/or bodily fluids of the user without theuse of, or necessity of, complicated monitoring systems that requireuser training and interaction. However, it will be recognized thatfurther embodiments of the invention may be used to determine the levelsof other analytes or agents, characteristics or compositions, such ashormones, cholesterol, medications concentrations, viral loads (e.g.,HIV), or the like. In other embodiments, the monitor system may alsoinclude the capability to be programmed to record data at specified timeintervals. The monitor system and analyte sensor are primarily adaptedfor use in subcutaneous human tissue. However, still further embodimentsmay be placed in other types of tissue, such as muscle, lymph, organtissue, veins, arteries or the like, and used in animal tissue. Theanalyte sensors may be subcutaneous sensors, transcutaneous sensors,percutaneous sensors, sub-dermal sensors, skin surface sensors, or thelike. Embodiments may measure and record sensor readings on anintermittent or continuous basis.

FIG. 1 is an exemplary illustration of components within a monitorsystem 100, in accordance with embodiments of the present invention. Thesensor 102 is shown from an exemplary top view as if it has beeninserted into a patient. In one embodiment the sensor 102 utilizes anelectrode-type sensor while in alternative embodiments, the sensor 102may use other types of sensors, such as chemical based, optical based orthe like. In further alternate embodiments, the sensor 102 may be of atype that is used on the external surface of the skin or placed belowthe skin layer of the user or placed in the blood stream of the user.Other embodiments of a surface mounted sensor would utilize interstitialfluid harvested from the skin.

In some embodiments, the sensor 102 is an assembly commonly known as a“sensor set” that includes, but it not limited to the connector 104,sensor adhesive (not shown) covered by an adhesive backing 106, anintroducer needle (not shown in FIG. 1), a sensing portion of the sensorto be placed in a body (not shown), and a mounting base 105. In oneembodiment the connector 104 is integrally injection molded from plasticwith the mounting base 105. The connector 104 further includeselectrical contacts that interface with contacts on the sensor. On aside opposite that shown in FIG. 1, the adhesive is applied to themounting base 105 and the adhesive backing 116 is further applied overthe adhesive.

An electronic package 108 is also included in the monitor system 100.The electronics package 108 includes a package housing 109 with apackage port 110. The package port 110 is designed to couple with theelectrical contact on the connector 104 thereby providing power andother electrical interfaces between the electronics package 108 and thesensor 102. In one embodiment the electronics package further includes apower source, processor and transmitter within the package housing 109.The power source provides power for the processor and transmitter andwhen coupled to the connector 104, further powers the sensor 102. Insuch an embodiment signals generated by an installed sensor can beprocessed via the processor and transmitted to another device such as,but not limited to infusion pump 112. In other embodiments, theelectronics package 108 includes at least a power source, processor,transmitter along with memory and a receiver. In these embodimentssensor signals from an installed sensor can be stored to memory withinthe package housing 109 and periodically transmitted to the infusionpump 112 or other devices configured to communicate with the electronicspackage 108. Additionally, the inclusion of the receiver within theelectronics package would enable two-way communication between otherdevices and the electronics package 108.

The inclusion of memory within the electronics package 108 can enablethe combined electronics package 108 and sensor 102 to be used as aHolter-type recording device that can use the package port 110 tointerface with either the sensor 102 or a docking station (not shown)that is further connected to a computer of tablet computing device. Whenused as a recording device the combined electronics package 108 andsensor 102 have the capability to record and store data as it isreceived from the sensor 102. When the electronics package 108 iscoupled to a docking station the data stored on the memory of theelectronics package 108 can be transferred to networked or local datastorage and analyzed using general computing processors such asdesktops, laptops, notebooks, netbooks, tablets, or handheld computingdevices such as, but not limited to smart phones and the like. To enabledata transfer through the dock, the dock may further include a datatransfer cable such as, but not limited to USB or Thunderbolt orEthernet directly coupled to a computing device.

The infusion pump 112 included in the monitor system 100 includes atubing 120 that is in connected to a reservoir 118 within the infusionpump 112. Other characteristics of the infusion pump include a display114 and a user interface 116. In some embodiments the display 114 is atouchscreen thereby making the display 114 an integrated component ofthe user interface 116. The infusion pump 112 can further include aradio transmitter and receiver that enables wireless communication. Insome embodiments the radio transmitter is a standard off the shelfBLUETOOTH radio that includes the BLUETOOTH LOW ENEGRY profile. In otherembodiments a custom secure radio transmission system is used. The radiotransmitter within the infusion pump 112 enables wireless transmissionwith the electronics package 108 thereby allowing sensor data to shownon the display 114.

Transmission of sensor data to the infusion pump 112 further enablesreal-time glucose monitoring which can further enable low-glucosesuspend functionality. In these embodiments if the sensor data indicatesa blood sugar level below a specified threshold, the infusion pump 112can suspend delivery of basal insulin. In some embodiments the rawsensor data measured by the sensor 102 is manipulated or processed usingthe processor within the electronics package 108 to determine sensordata from interstitial fluid that corresponds to a blood glucose level.In still other embodiments, the electronics package 108 transmits theraw sensor data to the insulin pump 112 where the raw sensor data isprocessed to correspond to a blood glucose level. In still otherembodiments, the electronics package 108 transmits both the raw sensordata and a first calculated blood glucose level to the insulin pump. Inthese embodiments the insulin pump can then use a different algorithm tocalculate a second blood glucose level from the raw sensor data. Thesecond blood glucose level then being used in conjunction with the firstblood glucose level to determine a third calculated blood glucose level.

Further description regarding the sensor and associated sensor set canbe found in U.S. Pat. No. 6,248,067, entitled ANALYTE SENSOR ANDHOLTER-TYPE MONITOR SYSTEM AND METHOD OF USING THE SAME, U.S. Pat. No.5,586,553, entitled TRANSCUTANEOUS SENSOR INSERTION SET, and U.S. Pat.No. 5,594,643, entitled DISPOSABLE SENSOR INSERTION ASSEMBLY, all ofwhich is herein incorporated by reference.

FIGS. 2A-2C are exemplary illustrations of placement of a sensor 102 andinstallation of the electronics package 108 onto the sensor 102, inaccordance with embodiments of the present invention. FIG. 2Aillustrates a sequence of typical steps used to place the sensor 102within interstitial fluid of a patient. The leftmost panel of FIG. 2A isillustrative of using an inserter 200 to assist in the installation orplacement of the sensor 102. Commonly, inserters 200 are customized toaccommodate a specific type of sensor 102. For additional informationregarding inserter 200 please see U.S. patent application Ser. No.10/314,653 filed on Dec. 9, 2002, entitled INSERTION DEVICE FORINSERTION SET AND METHOD OF USING THE SAME, U.S. Pat. No. 6,607,509,entitled INSERTION DEVICE FOR AN INSERTION SET AND METHOD OF USING THESAME, and U.S. Pat. No. 5,851,197 entitled INJECTOR FOR A SUBCUTANEOUSINFUSION SET, all of which are herein incorporated by reference.

The middle panel of FIG. 2A is an illustration showing the removal ofthe adhesive backing 106 to expose an adhesive that enables adhesion ofthe sensor 102 to skin 202 of a patient. The rightmost panel of FIG. 2Ais an illustration that depicts the removal of an introducer needle 204that is used during the placement of the sensor 102. FIG. 2B is anexemplary illustration showing the installation of the electronicspackage 108 onto the sensor 102. Direction arrows D₂ indicate that theelectronics package 108 is pushed onto the sensor 102 that was adheredto the patient, as shown in the middle panel of FIG. 2A. In someembodiments, it is desirable to wait a predetermined period of timebefore installing the electronics package 108 onto the sensor 102. Forexample, it may be advantageous to wait for up to 15 minutes for thesensor 102 to be properly hydrated or wetted by the patient'sinterstitial fluid before attaching the electronics package 108. Inother embodiments it may take longer or less time before is sensor isconsidered properly hydrated. Being able to detect if an installedsensor 102 is properly hydrated can be used by a practitioner to helpdetermine if the sensor was properly installed into the interstitialfluid. In other embodiments there is no minimum time required beforeattaching the electronics package 108 to the sensor 102. In still moreembodiments, the sensor 102 need not be hydrated before the electronicspackage 108 is connected. And in additional embodiments, the electronicspackage 108 may be integrated with the sensor before the sensor isinserted into a user. Once the electronics package 108 is coupled withthe sensor 102 some embodiments initialize the sensor based onalgorithms stored in the electronics package. During the initializationprocess algorithms can determine if the sensor is properly hydrated andwill most likely function as designed. In other embodimentsinitialization of the sensor is not required.

As illustrated in FIG. 2C, some embodiments of the electronics package108 include a feedback indicator 206. In one embodiment the feedbackindicator 206 is a light emitting diode (LED) that can be seen through atranslucent or semi-translucent housing. In other embodiments, differentlight elements can be used, such as, but not limited to incandescentlights, fluorescent lights, organic light emitting diodes (OLED) or thelike. In still other embodiments, the feedback indicator 206 can be anaudible tone or a vibration alarm similar to those in mobile phones. Inembodiments with the feedback indicator 206, the electronics package 108can provide feedback regarding the hydration level of a connectedsensor. For example, the recorder includes hardware and software thatcan determine if the sensor 102 is properly hydrated. The feedbackindicator 206 can help a practitioner by narrowing the type oftroubleshooting that needs to be performed. For example, the feedbackindicator 206 can be programmed to flash a specific sequence or color toindicate that the sensor 102 is properly hydrated. Similarly, thefeedback indicator 206 can be programmed to flash a different sequenceor color to indicate that the sensor is not properly hydrated. In otherembodiments, the feedback indicator 206 can further be programmed toflash a particular sequence or color that indicates to a practitionerthat the electronics package 108 is not fully charged or even that dataneeds to be transferred from the electronics package 108 beforeadditional data can be recorded. The examples provided are not intendedto be exhaustive of conditions that can be reported by the feedbackindicator 206. The particular examples provided are intended to beexemplary and should not be construed as limiting the scope of thepresent invention.

FIG. 3 is an exemplary block diagram illustrating components within theelectronics package 108, in accordance with one embodiment of thepresent invention. A power supply 212 connected to power management 218is found within the package housing 109 of the electronics package 108.In some embodiments the power supply 212 is a battery assembly that usesa rechargeable battery chemistry to provide power to the electronicspackage 108. In one embodiment the power supply 212 is made up oflithium ion battery cells. However, it is understood that alternatebattery chemistries may be used, such as nickel metal hydride, alkalineor the like. Similarly, various embodiments can use a single batterycell for a shorter life such as for a single-use disposable unit whileother embodiments use multiple battery cells that enable longer and/orreusable/rechargeable units.

In rechargeable embodiments the power management 218 includes circuitryand programming to allow recharging of the power supply 212 via thepackage port 110. In some embodiments power management 218 also includescircuitry and programming that enables a low battery warning alarm. Insome embodiments the power supply 212 is capable of enabling theelectronics package 108 to measure and/or record data for six days witha factor of safety of one additional day. Additionally, after six orseven days of measuring or recording data, the power supply furtherenables operation of an integrated clock in the electronics package 108for an additional seven days. Alternative embodiments may provide longeror shorter battery lifetimes, or include a power port or solar cells topermit recharging of the power supply 212.

The sensor 102 is connected via the connector 104 and the package port110 to a signal conditioning circuit 202, such as a potentiostat or thelike, in the package housing 109 of the electronics package 108. Thesignal conditioning circuit 202 is in turn connected to a current tofrequency converter (I to F) 204. The output of the current to frequencyconverter 204 is a digital frequency that varies as a function of thesensor signal produced by the sensor 102. In alternative embodiments,other signals, such as voltage, or the like, may be converted tofrequency. In one embodiment, the digital frequency is then counted by adigital counter 206, and a value from the digital counter 206 isperiodically read and stored with an indication of elapsed time, by amicroprocessor 208, into a non-volatile memory 210. In other embodimentsthe value from the digital counter 206 is sent to transmitter 211 fortransmission to, but not limited to, the infusion pump (not shown). Infurther embodiments the transmitter 211 additionally functions as areceiver thereby allowing two way communication between the electronicspackage 108 and the infusion pump.

In some embodiments, the electronics package 108 provides power to drivethe sensor 102 via the package port 110 and the connector 104. Powerfrom the electronics package 108 may also be used to speedinitialization of the sensor 102, when it is first placed under theskin. The use of an initialization procedure can result in a sensor 102providing stabilized data in an hour or less compared to requiringseveral hours before stabilized data is acquired without using aninitializing procedure. One exemplary initialization procedure uses atwo step process. First, a high voltage (preferably between 1.0-1.2volts—although other voltages may be used) is applied to the sensor 102for one to two minutes (although different time periods may be used) toinitiate stabilization of the sensor 102. Then, a lower voltage(preferably between 0.5-0.6 volts—although other voltages may be used)is applied for the remainder of the initialization procedure (typically58 minutes or less). The initialization procedure described above isexemplary and other initialization procedures using differing currents,voltages, currents and voltages, different numbers of steps, or thelike, may be used. In all embodiments the microprocessor 208 is furthercoupled to a fuse circuit 214. The fuse circuit 214 can be used to helplimit the number of uses of the sensor thereby ensuring sensors are notused beyond their expected lifecycle. Use of a sensor beyond itsexpected lifecycle can lead to erroneous and unreliable readings thatmay compromise the efficacy of therapy. Additional details regarding thefuse circuit will be discussed below.

FIGS. 4A-4D are exemplary views of the fuse circuit 214 in accordancewith embodiments of the present invention. FIG. 4A illustrates a basiccircuit diagram with switch 404 that is controlled by the microprocessor208. The charging of capacitor 402 would likewise be controller by themicroprocessor 208. Upon closing the switch 404 the capacitor 402 woulddischarge with enough energy to break fuse 400. FIG. 4B illustrateselements of the fuse circuit that are implemented on the connector 104from FIG. 1. As illustrated, fuse 400 is made by narrowing material thatalso makes up sensor detection pads 406 a and 406 b. The sensordetection pads 406 a and 406 b being shorted by fuse 400 serve as aswitch that signals to the electronics package that a sensor is pluggedin. In some embodiments, upon detecting the sensor, the electronicspackage initiates a timer for a first specified time. Once the firstspecified time has elapsed the capacitor 402 is charged and dischargedinto the shorted sensor detection pads 406 a and 406 b thereby breakingthe fuse 400. In some embodiments the sensor signals can continue untilthe sensor is disconnected or until a second specified time has elapsed.The breaking of the short between sensor detection pads 406 a and 406 bcan ensure that the sensor is only used once as the microprocessor canperform a check for shorted sensor detection pads 406 a and 406 b uponinitialization of a sensor.

FIGS. 4C and 4D are illustrations of a first side 408 and a second side410 of the connector 104, in accordance with an embodiment of thepresent invention. The first side 408 includes the previously discussedsensor detection pads 406 a and 406 b along with fuse 400. Locatedbetween the sensor detection pads 406 a and 406 b is an electricalcontact for a second working electrode 418. On the second side 410 ofthe connector 104 are the contacts for a counter electrode 412, a firstworking electrode 414 and a reference electrode 416. The relativeposition of the contacts should not be construed as limiting as thevarious locations can vary depending on how traces are made on thesensor.

FIG. 5A is an exemplary illustration of package port 110 that wouldreceive the connector 104 from the sensor, in accordance with oneembodiment of the present invention. The embodiment shown in FIG. 5A isa 10-pin connector that enables communication with the contact padsdiscussed in FIGS. 4A-4D while also providing additional electricalcontacts for power, transmitters and receivers. The particularembodiments discussed in detail below should not be construed aslimiting. Other embodiments can use various port and pin configurations.In still other embodiments, additional or fewer electrical contacts maybe implemented on both the package port and the connector to enable ordisable various sensor features. As shown in FIG. 5A pins 506 a and 506b are designed to interface with sensor detection pads 406 a and 406 b.Likewise, second working electrode pin 518 interfaces with secondworking electrode contact 418. Counter pin 512, first working electrodepin 515 and reference pin 516 interface respectively with countercontact 412, first working electrode contact 415 and reference contact416. Further included are ground pin 502, charge pin 504, transmitterpin 510 and receiver pine 516. For single-use embodiments, the chargepin 504 can be omitted.

FIGS. 5B-5D illustrate various embodiments of detail 520 of the recorderport 110, in accordance with embodiments of the present invention.Detail 520 shows top contacts 522 and bottom contacts 524 which togethercan simply be referred to as “electronics package contacts”. In theembodiment illustrated the electronics package contacts are mounted to acircuit board 526 to which the components described in FIG. 3 are alsomounted. The electronics package contacts can be board mounted springs,or simple contact pads, or any other variety of contact that creates areliable electrical connection.

The configuration illustrated is intended to be exemplary and should notbe construed to be limiting. For example, in alternative embodimentsshown in FIG. 5C, rather than a single recorder port 110 (FIG. 5A), thesensor 104 could have two separate ports with the first port 550providing access to top contacts 522 while the second port 552 providesaccess to bottom contacts 524. Similarly, other embodiments could usetwo separate ports while placing the bottom contacts 524 on the sameside of the circuit board 526 as the top contacts 522, as shown in FIG.5D.

FIG. 6 is an exemplary flow chart illustrating operations to initiate asensor with a fuse, in accordance with an embodiment of the presentinvention. The flow chart begins with START operation 600 followed byoperation 602 where the connector for the sensor is inserted into thepackage port. Operation 604 utilizes the microprocessor within theelectronics package to verify a short between the sensor detection pads.Operation 606 initiates a first timer and operation 608 determines ifthe first timer has reached the predetermined elapsed time. In someembodiments, the first timer allows the sensor to be used for 138 hours.In other embodiments, shorter or longer periods may be used for thefirst timer depending on the chemistry and configuration of the sensor.

Operation 610 charges and discharges the capacitor within the fusecircuit to break the fuse and open the short between the sensordetection pads. Operation 612 starts a second timer that is programmedto stop the sensor from functioning after a specific time has elapsed.In one embodiment, the second timer is set to run for six hours.Together with the initial 138 hours, this embodiment results in 144hours, or six days of sensor use. In other embodiments, six days ofsensor use may also be the total number of days of use but various timescan be used for the first timer and second timer to ensure the sensordoes not cease functioning while a user is asleep. Accordingly, thefirst time period may be shortened in order to increase the second timeperiod while still having the sensor operate for six days. In someembodiments the first and second timers are countdown timers that countdown from the predetermined elapsed time to zero. In other embodiments,the first and second timers count forward until the elapsed time is thesame as the predetermined elapsed time. In still other embodiments thefirst timer is a countdown timer and the second timer counts forward orvice versa. Operation 614 notifies the user via messages displayed onthe infusion pump that disconnecting the sensor will permanentlyterminate use of the sensor. In some embodiments operation 614 furtherdisplays the amount of time remaining until the sensor stops functioningon the display of the infusion pump.

In still other embodiments, the feedback indicator on the electronicspackage may begin blinking or flashing upon activation of the secondtimer. In some embodiments the color of the flashing LED of the feedbackindicator of the electronics package can change the longer the secondtimer is running. For example, upon initiation of the second time, theLED may flash a first color such as green. When about half the time ofthe second timer has elapsed, the LED switches to a second color such asyellow. Finally, when about a quarter of the time for the second timerremains, the LED switches to a third color such as, but not limited to,red. In addition to changes color, in other embodiments the LED feedbackindicator on the electronics package can also flash at different ratesdepending on how much time of the second timer remains. Operation 616terminates the sensor. In some embodiments the sensor may continue tooperate, but signals from the sensor are not processed or transmitted toother devices. In other embodiments sensor functionality is terminatedby disconnecting the power supply. Operation 618 ends the process.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A monitor system to transmit a real-timecharacteristic of a user, the system comprising: a sensor to producesignals indicative of a glucose characteristic measured in the user, thesensor comprising a connector; at least one element of a fuse systemimplemented on the connector, the at least one element of the fusesystem comprising at least two contacts shorted by a fuse trace, thefuse trace comprising narrowing material that also makes up the at leasttwo contacts; and an electronics package coupled to the sensor toreceive signals produced from the sensor, the electronics packagecomprising: a transmitter; a package port interfaced with the connectorto receive the signals produced from the sensor, a fuse timer; and apackage processor programmed to execute instructions of machine readableprogram code stored in non-volatile memory, wherein execution of theinstructions causes the package processor to perform steps comprising:processing the signals produced from the sensor and transmitting theprocessed signals via the transmitter, controlling the fuse system,wherein, in response to detecting that the package port is interfacedwith the connector of the sensor, initiating the fuse timer for aspecified time, and causing the fuse trace to be destroyed upon the fusetimer reaching a threshold value.
 2. The monitor system as described inclaim 1, wherein the sensor is initialized and confirmed by theelectronics package before the fuse timer is initiated.
 3. The monitorsystem as described in claim 2, wherein the sensor is initialized inresponse to detection of the at least two contacts being shorted by thefuse trace, wherein destruction of the fuse trace removes the shortthereby preventing reuse and re-initialization of the sensor.
 4. Themonitor system as described in claim 3, wherein the fuse system furtherincludes a capacitor.
 5. The monitor system as described in claim 4,wherein the package processor is programmed to execute instructionsfurther comprising charging the capacitor prior to the fuse timerreaching the threshold value.
 6. The monitor system as described inclaim 5, wherein upon reaching the fuse timer threshold value thecapacitor is discharged to destroy the fuse trace.
 7. The monitor systemas described in claim 6, wherein upon destroying the fuse trace theelectronics package initiates a second timer, the second timer having alimit of time before the sensor stops functioning.
 8. The monitor systemas described in claim 7, wherein an alarm indicates the second timer hasbeen initiated, the alarm providing feedback until the limit of time hasbeen reached and the sensor stops functioning.
 9. The monitor system asdescribed in claim 8, wherein the alarm comprises visual feedbackprovided by a flashing LED.
 10. A monitor system comprising: a sensor toproduce signals indicative of a real-time characteristic of a user, thesensor comprising a connector; at least one element of a fuse systemimplemented on the connector, the at least one element of the fusesystem comprising at least two contacts shorted by a fuse trace, thefuse trace comprising narrowing material that also makes up the at leasttwo contacts; and an electronics package interfaced with the connectorto receive signals produced from the sensor, the electronics packagecomprising: a transmitter; a fuse timer; and a package processorprogrammed to execute instructions of machine readable program codestored in non-volatile memory, wherein execution of the instructionscauses the package processor to perform steps comprising: processing thesignals produced from the sensor and transmitting the processed signalsvia the transmitter, controlling the fuse system, wherein, in responseto detecting that the electronics package is interfaced with theconnector of the sensor, initiating the fuse timer for a specified time,and causing the fuse trace to be destroyed upon the fuse timer reachinga threshold value.
 11. The monitor system of claim 10, wherein theelectronics package comprises a package housing that houses a powersource, the package processor and the transmitter.
 12. The monitorsystem of claim 10, wherein the electronics package further comprises afeedback indicator.
 13. The monitor system of claim 12, wherein thefeedback indicator further comprises a light element, an audible tone ora vibration alarm.
 14. The monitor system of claim 12, wherein thefeedback indicator is adapted to provide feedback regarding a hydrationlevel of the sensor.
 15. The monitor system of claim 12, wherein thefeedback indicator is adapted to provide feedback indicating that theelectronics package is not fully charged.
 16. The monitor system ofclaim 10 wherein the transmitter additionally functions as a receiverallowing two way communication between the electronics package and aninfusion pump.
 17. The monitor system of claim 10, wherein the fusesystem further comprises a switch and a capacitor, wherein upon closingthe switch, the capacitor discharges energy to break the fuse trace. 18.The monitor system of claim 17, wherein, upon determining that thespecified time has elapsed, the capacitor charges and discharges intothe at least two contacts shorted by the fuse trace thereby breaking thefuse trace.
 19. The monitor system of claim 18, wherein the producedsignals from the sensor continue until the sensor is disconnected oruntil a second specified time has elapsed.